Camshaft

ABSTRACT

A camshaft as used to actuate a plurality of spring returned followers. The camshaft resists the bending loads imposed on it by utilizing a rigid tubular construction in which the inside diameter tapers to a minimum near the center of the length of the camshaft resulting in greater material strength at a section furthest from the bearing support at either end.

United States Patent lnventor Warren L. Harvey New Providence, NJ (P10. Box 622 West Main St., Mendham, N.J., 07945) Appl. No. 838,097 Filed July 1, 1969 Patented May 4, 1971 CAMSHAFI 1 Claim, 3 Drawing" Fig.

U.S. Cl 74/567 Int. Cl F16h 53/02 Field of Search 74/567, 568; 123/90, 190 (Comp) References Cited UNITED STATES PATENTS 2,473,417 6/1949 Essl 74/568 2,888,837 6/1959 Hellman 74/568 FOREIGN PATENTS 817,382 9/1937 France 74/567 Primary Examiner-William F. ODea Assistant Examiner-F. D. Shoemaker ABSTRACT: A camshaft as used to actuate a plurality of spring returned followers. The camshaft resists the bending loads imposed on it by utilizing a rigid tubular construction in which the inside diameter tapers to a minimum near the center of the length of the camshaft resulting in greater material strength at a section furthest from the bearing support at either end.

CAMSHAFI This inventionrelates in general to camshafts and more particularly to camshafts as used to actuate valve gear in multiple cylinder 4 cycle combustion engines.

Desirable features of a camshaft with a length sufiicient to accommodate followers appropriately spaced to actuate spring returned valve gear for a fouror more cylinder fourcycle internal combustion engine are a rigidity sufficient to withstand bending loads imposed by the spring returned valve gear and a high degree of alignment with respect to the supporting bearings. Also highly desirable is a cam profile with a nonjarring lift and return motion.

In current practice, camshafts of the aforementioned length utilize supporting bearings spaced along the shaft to gain the necessary rigidity. Misalignment of these bearings and/or bending of the camshaft results in binding leading to failure.

A new manner of operation is employed by the present invention whereby the rigidity is incorporated into the camshaft instead of utilizing external support thereby reducing the number of required bearings to a minimum. Accordingly, it is an object of the invention to reduce bearing frictional drag and misalignment to a minimum. An inherent feature of the invention is an improved cam profile.

These and other objects and advantages will become more apparent from the following description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a section through center of the camshaft and supporting bearings with fragmentary section of the engine block shown.

FIG. 2 is a section view through the shaft along line 4 of FIG. 1.

FIG. 3 is a section view along line 5 of FIG. 1 showing a typical cam profile.

With reference to the drawings the invention is shown as a camshaft 10 with a tubular section and a length sufficient to accommodate followers appropriately spaced to actuate spring returned valve gear for a fouror more cylinder fourcycle internal combustion engine. Said camshaft 10 is supported only at each end by bearings 11 which are located in the engine block 12. Use of a two-position bearing support system reduces misalignment to a practical minimum and is unique in that self-aligning bearings may be employed.

In operation the loads imposed by said spring-returned valve gear are transmitted to said camshaft 10 which transmits said load to said engine block 12 through said bearings 11. Whereas bending is prevented only by the structure of said Camshaft 10, the outside and inside diameters of said camshaft 10 are increased to the appropriate magnitude to achieve the necessary rigidity with regard to distance between loading and support. The minimum diameter of the cam profile is thus subordinate to the structural requirements in that the minimum diameter of said cam profile is greater than or equal to said outside diameter. Utilizing known materials said invention will necessitate a larger minimum diameter of cam profile than that of a standard bearing supported camshaft of similar length. With the valve lift remaining constant said invention will have a proportionately lesser change from minimum diameter cam dwell to maximum diameter cam dwell resulting in an inherently less steep physical cam profile per given requirements of lift and dwell.

lclaim:

l. A camshaft of a length sufiicient to accommodate followers appropriately spaced to actuate spring returned valve gear for a fouror more cylinder four-cycle internal combustion engine wherein said camshaft is tubular whereby the inside diameter decreases from a maximum at each end to a minimum near the center of the length of said camshaft. 

1. A camshaft of a length sufficient to accommodate followers appropriately spaced to actuate spring returned valve gear for a four- or more cylinder four-cycle internal combustion engine wherein said camshaft is tubular whereby the inside diameter decreases from a maximum at each end to a minimum near the center of the length of said camshaft. 